step(umc2,ci,tm(s,[ctxm(alpha_2_,umc,ip, (ip,umc2), (ip,umc2)),ctxm(alpha_2_,ci,ip, (ip,ci), (ip,ci))],pri(lst,[pri(h,[ctxm(alpha_2_,u,bsn,i_bsn,i_bsn)]),ctxm(alpha_2_,u,d_4, (i,d_4), (c,d_4)),ctxm(alpha_2_,u,d_5, (i,d_5), (c,d_5)),ctxm(alpha_2_,u,d_6, (i,d_6), (c,d_6))]))).